The invention relates to devices and methods for making plumbness measurements of building frame structures, especially when the measurements must be made of the plumbness of bowed or warped vertical studs of the frame structures and when the vertical studs are of various lengths.
By way of background, those skilled in the art of constructing building frames know that the studs of framed walls are rarely truly vertical immediately after the frames are erected. The studs therefore must be measured and adjusted for "plumbness", or true verticalness". The typical approach of erecting frame walls is to utilize premarked horizontal lower plates that are attached to the top of the foundation or floor structure. The lower ends of the vertical studs are attached to the lower plates at the spaced, premarked locations thereof. The upper ends of the studs are attached to similarly spaced, premarked locations of a horizontal (or, in some cases, sloped, "top plate". The frame wall is temporarily held in place by braces. The studs may be of the same or varying lengths, depending on the type of roof structure utilized. In any case, the studs, whether they are of metal or wood, but especially if they are of wood, are rarely perfectly straight, and they are rarely perfectly vertical. One reason the studs are rarely vertical is non-levelness of the floor or foundation to which the bottom premarked plates are attached. Furthermore, even if wood studs are initially straight, a few hours of exposure to sunlight usually causes them to warp, sometimes severely. This warpage makes it difficult for a worker to subsequently make measurements indicative of the plumbness of individual studs and of the framed wall as a whole. Nevertheless, the plumbness must be measured and adjustments of the "verticalness" of the measured studs and the wall must be made in the most efficient and accurate way that is practical, because otherwise numerous difficulties will be encountered in subsequent construction of the building.
If a typical carpenter's level having flat, parallel opposed edge surfaces and also having both a horizontal bubble vial and a vertical bubble vial is used, a number of difficulties may be encountered. Usually, the carpenter's level is considerably shorter than the studs which must be measured in order to adjust plumbness. To measure plumbness of a warped stud, the flat edge surface of the carpenter's level must be placed against either the convex or the concave surface of the warped stud. Those skilled in the art know that the resulting measurements and adjustments of plumbness of the warped stud is therefore based on "guesswork" as to against which portion of the warped stud the relatively short carpenter's level should be abutted to obtain an accurate indication of the stud's plumbness. Due to the inherent inaccuracy of this approach, the common practice is for the worker whose responsibility it is to measure plumbness to find the straightest unused stud of the needed length that he can and nail two equal thickness blocks to the upper and lower ends respectively, of that stud. In order to make the needed plumbness measurement, the worker then holds the nailed-on block of the modified stud against the end points of the stud to be plumbed. He then holds a flat edge surface of the carpenters level against the straight stud.
Although this technique provides the needed accuracy of measurement, it is quite inconvenient, especially if no adequately straight stud can be found. Furthermore, if the roof structure of the building under construction is of the type sometimes referred to as a "shed roof", the studs of a wall may be all of different lengths. In this case, it is obviously inconvenient and impractical to use the above technique. However, it may be difficult to obtain accurate plumbing measurements without making a number of the above-described makeshift devices.
It is clear that the unavailability of a readily made, easily used, extendable length plumbing device results in inefficient use of workers' time in constructing and using the above makeshift devices, and also leads to imprecision in the plumbness of the walls of the completed structure and lower than desirable quality of construction.
A variety of plumbing tools and aids are known, including those disclosed in U.S. Pat. Nos. 686,360; 3,328,887; 1,780,344; 945,275 which are listed in order of decreasing relevance to the present invention. U.S. Pat. No. 686,360 discloses an extendable device with two offset elements 10 attached to members that are respectively extendable from opposite ends of the main body, which includes a vial for making plumb measurements. This device is of rather imprecise construction, and is extendable to a length that is only less than twice the length of the main body. Furthermore, the device does not have a flat edge surface that is useful for simultaneously making flatness, as well as plumbness measurements. But those skilled in the art know that both types of measurements must be made in "plumbing up" a newly erected frame structure, especially in "plumbing up" and shimming door jambs. Typically, a prefabricated door is perfectly rectangular, but a door jamb erected in a frame structure usually is not straight, and instead is warped in one or two directions, and it also usually is "out of plumb" in one or two directions. The device disclosed in U.S. Pat. No. 686,360 is not suitable for measuring both plumbness and flatness of door jambs. Furthermore, it is not easily extendable, because set screws must be loosened to allow extension of the device and then must be tightened to maintain the extended length. Furthermore, the device shown in U.S. Pat. No. 686,360 is not easily retrofittable to standard commercially available carpenter's levels.
It is clear that there is an unmet need for a single inexpensive, highly accurate device which can be used as a plumbness measurement tool that is easily and quickly extendable to many desired practical working lengths, is easily locked into an extended configuration, has a flat surface that enables accurate measurements of both flatness and plumbness, and is easily attachable to carpenter's levels of conventional design.
Accordingly, it is an object of the invention to provide an improved extendable apparatus for efficient working of plumbing measurements.
It is another object of the invention to provide an apparatus that makes it easy for a worker to quickly make plumbness measurements and flatness measurements to "plumb up" a frame structure of walls of a building before continuing further construction of the walls.
It is another object of the invention to provide a plumbing device which is extendable and has a quick release mechanism for allowing extension and locking of the device into an extended configuration or allows rapid collapsing of the extended device into a compact configuration.
It is another object of the invention to provide a device that is useful in making accurate plumbness measurements of warped studs and flatness measurements of door jambs.